This invention relates to an alarm device for marine propulsion units and more particularly to an improved and simplified alarm system for a marine propulsion system having plural engines and drive arrangements.
In many forms of marine application, there are provided pairs of driving engines and propulsion devices. In accordance with these systems, there are provided either warning or protection systems for each engine for either providing an operator warning or engine protection in the event of certain abnormal conditions. For example, if there is an overheating, lack of lubricant or some other abnormal condition, the engine may be protected by reducing its speed and/or an alarm may be given for the operator. However, with one engine malfunctioning and the other engine operating normally, the operator may not notice the warning signal and might continue to operate the watercraft at full speed. As a result, the abnormally running engine may be oversped by the passage of the water across its propeller and damage could result.
There has, therefore, been proposed a system in which either the warning indicators or engine protection circuits of both engines are activated in the event of a malfunction of either one of them. Such an arrangement is shown in U.S. Pat. No. 4,708,669, entitled "Warning Device For A Watercraft Provided With A Plurality Of Marine Propulsion Engines," issued Nov. 24, 1987 in the names of Isao Kanno et al and assigned to the assignee of this application. Although that system is particularly useful and advantageous, as the number of abnormal conditions sensed for the individual propulsion units increases, the complexity of the circuit for providing the warning signal and/or protection control for the normally running engine becomes very complicated and complex.
It is, therefore, a principal object of this invention to provide an improved and simplified warning device for a marine propulsion unit.
It is a further object of this invention to provide a simplified warning and protection arrangement for plural marine propulsion units wherein a wide variety of abnormal conditions are sensed.